Given a 4x4 matrix with rows I to IV and columns I to IV, letters are placed such that meaningful 4-letter words are formed in each column (top to bot...

Given a 4x4 matrix with rows I to IV and columns I to IV, letters are placed such that meaningful 4-letter words are formed in each column (top to bottom) and each row (left to right). The coding rule for letters is: A-1, B-2, C-3, D-4, E-5, F-1, G-2, H-3, I-4, ..., Y-5, Z-1. The cell value is the sum of the place values of its row and column. No letter repeats more than twice in the entire matrix. If a letter appears once in a row or column, it must not appear again in that row or column.

Known letters in columns:

• Column I: positions I, II, IV are V, A, T respectively
• Column II: positions III, IV are H, O respectively
• Column III: position II is R
• Column IV: positions I, III, IV are N, T, S respectively

Which alphabet should be placed at position (III, III) to form meaningful words in row III and column III?